输气管道计划放空方式对比

Comparison analysis on the scheduled venting modes of gas pipelines

放空系统是长距离输气管道的重要设施,对于保障管道维抢修安全、降低管道事故危害具有重要作用。基于现有放空设施,选择合理的放空方式,有利于降低放空不利影响,保护操作人员作业安全。在对输气管道放空设施及放空过程合理简化的基础上,通过TGNET软件模拟确定了一段式、两段式、三段式、六段式及固定流量5种放空方式的放空流量、温度及压力变化。采用FLARENET和PHAST软件确定了不同放空方式的最大泄放流量对应的马赫数、噪音强度及天然气扩散半径。结果表明:在计划放空过程中,放空阀操作次数越多、天然气泄放流量越均衡,引发的温降、噪声及天然气扩散等不利后果的影响越小。因此,建议采用固定流量放空作为首选放空方式,如果难以满足固定流量放空的条件,应尽可能多次调解放空阀开度,以减少放空产生的不利后果。(图7,表2,参25)

Venting system is an important facility of long-distance gas pipeline,and it plays an important role in ensuring the safety of pipeline maintenance and repair and reducing the damage of pipeline accidents.To select a reasonable venting mode on the basis of existing venting facilities is favorable for reducing the adverse effects of venting and ensuring the safety of operators.In this paper,the venting flow,temperature and pressure changes of 5 venting modes(i.e.,single-stage venting,two-stage venting,three-stage venting,six-stage venting and constant rate)were simulated by the software TGNET after the venting facility and process of the gas pipeline were simplified rationally.Then,the Mach number,noise intensity and natural gas diffusion radius corresponding to the maximum venting rates in different venting modes were calculated by FLARENET and PHAST.It is shown that during the scheduled venting,the more frequently the venting valves are operated,the stabler the venting rate of natural gas is and the less the adverse effect of temperature drop,noise and natural gas diffusion is.Therefore,it is recommended to adopt the constant-rate venting as the preferred venting mode of natural gas pipelines.If the conditions of constant-rate venting cannot be met,it is necessary to regulate the opening of venting valves as many times as possible in order to reduce adverse consequences of venting.(7 Figures,2 Tables,25 References)